A Combined Petrographic and Micro-Raman Study of Meteoritic Microdiamond in ALH-77257 Ureilite and ALH-78113 Aubrite

Gyollai, I.; Gucsik, A.; Vereš, M.; Koós, M.; Nagy, Szabolcs

doi:10.1080/00387010.2011.627527

Cited by 4 publications

(2 citation statements)

References 12 publications

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“…При возбуждении КР в алмазных микрои нанокристаллах различными источниками лазерного излучения наблюдаются дополнительные полосы, которые могут принадлежать примесям графита [14] и аморфного углерода [15]. Увеличение длины волны возбуждающего излучения приводит к появлению в спектре КР CVD-пленок микро-и нанокристаллов алмаза многочисленных " биений" и высокоинтенсивного фона в области частот до фундаментальной моды 1332 cm −1 [13,16,17].…”

Section: Introductionunclassified

Микрокристаллические Алмазные Порошки Как Перспективные Объекты Для Генерации Многочастотного Вынужденного Комбинационного Рассеяния-=sup=-*-=/Sup=-

Горелик¹,

Скрабатун²,

Bi³

2019

Журнал Технической Физики

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The laws of Raman scattering in microcrystalline diamond powders are investigated depending on the size of diamond microresonators in the range of 1–600 mkm. The observed effect of the anomalously high intensity of spontaneous Raman scattering in diamond microresonators is explained by the “trapping” of electromagnetic radiation in them, the wavelength of which is smaller than the size of diamond microcrystals. Due to the "trapping" of photons in diamond microresonators, the density of electromagnetic energy for excitation and secondary radiation increases. The high quality factor of the fundamental optical mode in the vibrational spectrum of diamond and the anomalous increase in the intensity of Raman scattering in diamond microresonators open up possibilities for observing low-threshold stimulated multifrequency Raman scattering in microcrystalline diamond powders. The use of the generation lines of a pulsed solid-state YAG: Nd3+ laser (λ = 1064 nm) and its optical harmonics (λ = 1064, 532, 354, 266 nm) as exciting radiation makes it possible to create a line of laser-frequency oscillators from the ultraviolet region that are equidistant in frequency shift to the terahertz range, promising for the study of biological and medical objects.

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Section: Introductionunclassified

Микрокристаллические Алмазные Порошки Как Перспективные Объекты Для Генерации Многочастотного Вынужденного Комбинационного Рассеяния-=sup=-*-=/Sup=-

Горелик¹,

Скрабатун²,

Bi³

2019

Журнал Технической Физики

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“…in Nakamuta et al ( 17)), whereas there is no evidence that such temperatures were ever reached (equilibration temperatures were 70-200°C cooler (1)). The observed strong enrichment of noble gases in ureilite diamonds and lack in coexisting graphite has also been difficult to reconcile with a shock origin (21,22). The high noble gas content led to suggestions that the diamonds formed through chemical vapor deposition (CVD) in the solar nebula prior to incorporation into the UPB (23)(24)(25)(26).…”

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confidence: 99%

Sequential Lonsdaleite to Diamond Formation in Ureilite Meteorites via In Situ Chemical Fluid/Vapor Deposition

Tomkins

Wilson

MacRae

et al. 2022

Proc. Natl. Acad. Sci. U.S.A.

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Ureilite meteorites are arguably our only large suite of samples from the mantle of a dwarf planet and typically contain greater abundances of diamond than any known rock. Some also contain lonsdaleite, which may be harder than diamond. Here, we use electron microscopy to map the relative distribution of coexisting lonsdaleite, diamond, and graphite in ureilites. These maps show that lonsdaleite tends to occur as polycrystalline grains, sometimes with distinctive fold morphologies, partially replaced by diamond + graphite in rims and cross-cutting veins. These observations provide strong evidence for how the carbon phases formed in ureilites, which, despite much conjecture and seemingly conflicting observations, has not been resolved. We suggest that lonsdaleite formed by pseudomorphic replacement of primary graphite shapes, facilitated by a supercritical C-H-O-S fluid during rapid decompression and cooling. Diamond + graphite formed after lonsdaleite via ongoing reaction with C-H-O-S gas. This graphite > lonsdaleite > diamond + graphite formation process is akin to industrial chemical vapor deposition but operates at higher pressure (∼1–100 bar) and provides a pathway toward manufacture of shaped lonsdaleite for industrial application. It also provides a unique model for ureilites that can reconcile all conflicting observations relating to diamond formation.

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Csátalja, the largest H4–5 chondrite from Hungary

Kovács¹,

Sajó²,

Márton³

et al. 2015

Planetary and Space Science

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A Combined Petrographic and Micro-Raman Study of Meteoritic Microdiamond in ALH-77257 Ureilite and ALH-78113 Aubrite

Cited by 4 publications

References 12 publications

Микрокристаллические Алмазные Порошки Как Перспективные Объекты Для Генерации Многочастотного Вынужденного Комбинационного Рассеяния-=sup=-*-=/Sup=-

Микрокристаллические Алмазные Порошки Как Перспективные Объекты Для Генерации Многочастотного Вынужденного Комбинационного Рассеяния-=sup=-*-=/Sup=-

Sequential Lonsdaleite to Diamond Formation in Ureilite Meteorites via In Situ Chemical Fluid/Vapor Deposition

Csátalja, the largest H4–5 chondrite from Hungary

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